In semiconductor device manufacturing involving semiconductor die bonding, it is common to change a collet of a bond head used for pick-and-place operations when bonding a die with a different size. This is to ensure that a collet of a correct size is utilized to hold the die securely when conducting such die bonding operations. A typical method to mount a changeable collet to a bond head mount is by vacuum suction of the collet to the bond head mount. Conventionally, there has been no concern with a surface area of the collet which interfaces with the bond head mount being the same size as a corresponding interface on the bond head mount. Usually, it is possible to maintain the same interface surface area for the collet to the bond head mount as the collet has a protruding area that is used to support the die. Thus, only a perimeter of the protruding area needs to be changed to support different die sizes, whereas the collet itself does not require any dimensional change for connection to the bond head mount.
FIG. 1 is an isometric view of a prior art bond head heater 100 of a bond head used for picking up semiconductor dice and to perform die bonding. A collet (not shown) is attached to the bond head heater 100 such that a die may be heated when it is being held by the collet. As can be seen from FIG. 1, the bond head heater 100 comprises a collet vacuum hole 102 and vacuum grooves 106 connected to the collet vacuum hole 102 for spreading a vacuum suction force over a wider area when attaching a collet. Thus, the collet vacuum hole 102 and vacuum grooves 106 are both incorporated into the bond head heater 100. There is also a die vacuum hole 104 providing a vacuum suction force for holding a die.
This prior art bond head heater 100 is designed so that a flat collet can be held by vacuum suction throughout the locations of the vacuum grooves 106. Hence, with the existing design, collets having multiple sizes are attachable to the bond head heater 100. However, the vacuum system comprising the vacuum grooves 106 becomes unnecessarily complicated.
Moreover, some thermal compression die bonding operations involve extremely rapid temperature changes. In order to achieve such rapid temperature changes, there is a need to reduce a thermal mass of the collet. One way to produce a collet with lower thermal mass is to reduce a volume of the base material of the collet.
The prior art bond head heater 100 which includes the collet vacuum hole 102 and vacuum grooves 106 incorporated into it requires the collet that is attached to it to have one or more predetermined collet interface surface areas. If differently-sized collet interfaces are to be used, more than one vacuum groove 106 is typically required, such that a few rings of vacuum grooves 106 should be formed, as illustrated in FIG. 1. A disadvantage of this approach is that more than one vacuum groove 104 is required to enable the bond head heater 100 to hold collets of different sizes. Even then, only a limited number of collet sizes are allowed depending on the number of rings formed, such that three rings of vacuum grooves 104 generally only allow for three different collet sizes to be attached. Furthermore, with the fixed vacuum area on the heater, it is not easy to maintain a contact area ratio to generate a sufficiently high heat flux for rapid heating of silicon dice, particularly for smaller collets.